JAKARTA - An earthquake struck Indonesia's Mentawai islands off Sumatra on Wednesday, but no tsunami warning was issued and there were no immediate reports of damage, an official from the country's meteorology agency said.

The U.S. Geological Survey said the quake measured magnitude 5.9 and was at a depth of 19 km (12 miles), with its epicentre 113 km (180 miles) west-southwest of Padang, the capital of West Sumatra province.

"There is no potential for a tsunami. I am in Padang and on the sixth floor and I felt the quake, but it was not really big," said Fauzi, head of the seismology centre at the agency.

More than 1,000 people died when a powerful earthquake hit the city of Padang in September.

Indonesia sits on the so-called "Pacific Ring of Fire," an area of intense seismic activity around the Pacific Ocean.